Studies of voluntary movement focused on the role of the cerebellum. One issue was the contribution of the cerebellum to coordination. The results seem to indicate that the cerebellum is critical for the coordination of multijoint movement. The role of the cerebellum is more important as the speed of movement increases. A second issue is the role of the cerebellum in motor learning. In tasks of motor skill learning, it has been demonstrated that patients with cerebellar disturbances can learn, but the learning is limited when the speed of the movement is greater. We have also studied the contribution of the cerebellum to conditioning. Patients with cerebellar deficits have a marked disorder of acquisition of conditioned eyeblink. A therapeutic trial of 5-HTP for cerebellar ataxia was stopped when a probable case of eosinophilia myalgia syndrome occurred. Using 0-15 labelled water as a marker for cerebral blood flow in positron emission tomography ( PET) studies, we have been working on methods for improved anatomic correlation of regions of metabolic change by superimposing the PET image onto an MRI image. Regions of the brain activated with voluntary movement, vibration of the hand and eve movement have been identified and quantified. A special study was devoted to the role of parietal cortex in the control of reaching. Studies include analysis of the role of the cerebellum in motor learning and the supplementary motor area in self-paced movement. Studies of movement-related cortical potentials have focused on identifying dipoles for the generation of the different components and the development of techniques for measuring event related desynchonization of the EEG. Studies have been completed in patients with dystonia that show reduction in amplitude of some components. Studies in the Biomechanics Laboratory of the Department of Rehabilitation Medicine have focused on the control of balance and gait. A study has been completed of gait in patients with autism that shows no systematic abnormality. A similar project in patients with cerebellar disorders is in progress. Other studies are being done of balance in patients with cerebellar deficits.